CN107390149B - gradient coil polarity detection method, storage medium and magnetic resonance scanning system - Google Patents
gradient coil polarity detection method, storage medium and magnetic resonance scanning system Download PDFInfo
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- CN107390149B CN107390149B CN201710602600.9A CN201710602600A CN107390149B CN 107390149 B CN107390149 B CN 107390149B CN 201710602600 A CN201710602600 A CN 201710602600A CN 107390149 B CN107390149 B CN 107390149B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
- G01R33/38—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field
- G01R33/385—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field using gradient magnetic field coils
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
- G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
- G01R33/36—Electrical details, e.g. matching or coupling of the coil to the receiver
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Abstract
the invention relates to a method for detecting the polarity of a gradient coil, which comprises the following steps: receiving radio frequency signals of an imaging subject by a radio frequency coil, the radio frequency coil comprising at least one radio frequency coil unit; acquiring a radio frequency signal of a radio frequency coil unit, the radio frequency coil unit being located in a first direction along an axis to be measured of the gradient coil with respect to the imaging subject; calculating the signal intensity distribution of the radio-frequency signals along the axis to be measured after signal reconstruction based on the obtained radio-frequency signals of the radio-frequency coil unit, and determining a second direction of the radio-frequency coil unit along the axis to be measured relative to the imaging object according to the signal intensity distribution; and determining whether the polarity of the axis to be measured is reversed or not according to the first direction and the second direction. The method for detecting the polarity of the gradient coil can quickly and timely detect whether the polarity of the gradient coil is reversely connected. The invention also relates to a storage medium and a magnetic resonance scanning system.
Description
Technical Field
The invention relates to the field of medical equipment, in particular to a gradient coil polarity detection method, a storage medium and a magnetic resonance scanning system.
Background
In a magnetic resonance scanning system, a gradient coil comprises linear gradient fields in three orthogonal directions of X, Y and Z, and has the functions of layer selection, frequency encoding, phase encoding, flow velocity encoding, flow compensation, diffusion detection and the like. They can also be used to adjust the main magnetic field homogeneity, which is beneficial to improve the image signal-to-noise ratio, homogeneity and geometric position accuracy. The gradient coils are looped with specific power output components, and the currents generated by the power output components are relied on to generate specific magnetic fields. In the production and integration engineering of a gradient system, errors in the positive and negative polarity directions of a loop may occur, in this case, the image direction may be disordered, the image may be deformed, and even seriously, the magnet uniformity may be too poor to acquire a magnetic resonance signal.
generally, the error of reverse polarity of the coil is rarely generated in the production and integration process by strictly controlling the process and the foolproof design of the switching part, and once the problem occurs, the problems of serious deformation of a normal scanning image, too low signal and the like can be caused, so that the problem is very difficult to be checked. In addition, the conventional art may use a member for assisting the current coupling detection to detect the direction of the current in the coil circuit to detect the polarity of the coil, but this method requires the provision of an auxiliary detection device, and thus has disadvantages in cost and serviceability.
Disclosure of Invention
in view of the above, it is necessary to provide a method for detecting polarity of gradient coil, a storage medium and a magnetic resonance scanning system, which are directed to the problems of high cost and inconvenience in timely detection caused by the need of providing auxiliary detection equipment in the conventional method for detecting polarity of gradient coil.
A method of detecting polarity of a gradient coil, comprising the steps of:
Receiving radio frequency signals of an imaging subject by a radio frequency coil, the radio frequency coil comprising at least one radio frequency coil unit;
Acquiring a radio frequency signal of a radio frequency coil unit, the radio frequency coil unit being located in a first direction along an axis to be measured of the gradient coil with respect to the imaging subject;
calculating the signal intensity distribution of the radio-frequency signals along the axis to be measured after signal reconstruction based on the obtained radio-frequency signals of the radio-frequency coil unit, and determining a second direction of the radio-frequency coil unit along the axis to be measured relative to the imaging object according to the signal intensity distribution; and
And determining whether the polarity of the axis to be measured is reversed or not according to the first direction and the second direction.
Further, determining whether the polarity of the axis to be measured is reversed according to the first direction and the second direction comprises:
If the first direction is the same as the second direction, determining that the polarity of the axis to be measured of the gradient coil is not reversed; and
And if the first direction is opposite to the second direction, determining that the polarity of the axis to be measured of the gradient coil is reversed.
further, before the receiving the radio frequency signal of the imaging object by the radio frequency coil, the method further comprises:
and emitting radio frequency pulses through a radio frequency coil to carry out radio frequency excitation on the imaging object, and exciting the imaging object to emit radio frequency signals.
Further, before the radio frequency coil emits the radio frequency pulse to perform radio frequency excitation on the imaging object, the method further comprises the following steps:
An imaging subject is placed within the radio frequency coil.
Further, the imaging object is a spherical water model.
Further, the signal intensity distribution is displayed in the form of a one-dimensional projection waveform along the gradient coil axis of interest.
Further, the signal intensity distribution is displayed in the form of a two-dimensional image along the gradient coil axis of interest.
A magnetic resonance scanning system comprising a magnetic resonance scanning apparatus and a computer, wherein the computer comprises a processor, a storage medium, and a computer program stored on the storage medium and executable on the processor, the program when executed by the processor being operable to perform a method of detecting polarity of a gradient coil, the method comprising:
receiving radio frequency signals of an imaging subject by a radio frequency coil, the radio frequency coil comprising a plurality of radio frequency coil units;
acquiring a plurality of radio frequency signals of a plurality of radio frequency coil units, the plurality of radio frequency coil units being located in a corresponding first direction, third direction and/or fifth direction along the axis of interest of the gradient coil relative to the imaging subject;
On the basis of the radio-frequency signals, calculating signal intensity distribution of the radio-frequency signals along the axis to be measured after signal reconstruction, and determining a second direction, a fourth direction and/or a sixth direction of the radio-frequency coil units relative to the imaging object along the axis to be measured according to the signal intensity distribution; and
And determining whether the polarity of the axis to be measured is reversed or not according to at least one group of direction combinations formed by the first direction, the second direction, the third direction, the fourth direction, the fifth direction and the sixth direction.
Further, determining whether the polarity of the axis to be measured is reversed according to at least one of the combinations of the first direction and the second direction, the third direction and the fourth direction, and the fifth direction and the sixth direction comprises:
If the two directions in the direction combination are the same, determining that the polarities of the axes to be measured of the corresponding gradient coils are not reversed; and
And if the two directions in the direction combination are opposite, determining that the polarity of the axis to be measured of the corresponding gradient coil is opposite.
A storage medium having stored thereon a computer program executable by a processor for performing the above mentioned gradient coil polarity detection method.
according to the gradient coil polarity detection method, the storage medium and the magnetic resonance scanning system, the detection data is calculated and evaluated mainly in a magnetic resonance signal one-dimensional projection mode without imaging, so that the detection speed is higher, an imaging object does not need to be moved in the detection process, the detection operation is more convenient, and the detection can be carried out in time.
drawings
fig. 1 is a flowchart of a gradient coil polarity detection method according to an embodiment of the present invention.
FIG. 2 is a distribution plot of a plurality of radio frequency coil units in a radio frequency coil along an X-axis of a gradient coil.
Fig. 3 and 4 are two-dimensional images of an imaging subject along the X-axis for both the non-reversed and reversed polarity of the X-axis of the gradient coil.
FIG. 5 is a one-dimensional projection of a waveform of an imaging subject along the X-axis for both the non-reversed polarity and reversed polarity of the X-axis of the gradient coil.
FIG. 6 is a waveform diagram of the RF pulse, the gradient signal and the feedback RF signal in the present invention.
Figure 7 is a block diagram of a magnetic resonance scanning system in accordance with an embodiment of the present invention.
Figure 8 is a schematic structural diagram of a magnetic resonance scanning system in accordance with an embodiment of the present invention.
Detailed Description
in order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
As shown in fig. 1, an embodiment of the present invention provides a method for detecting polarity of a gradient coil, including the following steps:
Step S1: an imaging subject is placed within a radio frequency coil that includes a plurality of radio frequency coil units.
Step S2: the radio frequency coil emits radio frequency pulses to carry out radio frequency excitation on the imaging object, and the imaging object is excited to emit radio frequency signals.
step S3: radio frequency signals of an imaging subject are received by a radio frequency coil.
step S4: radio frequency signals of a radio frequency coil unit are acquired, the radio frequency coil unit being located in a first direction along an axis of interest of the gradient coil relative to the imaging subject.
the gradient coil is provided with a gradient coil axis of measurement, wherein the gradient coil axis of measurement has two directions, one of which is along the extension direction of the gradient coil axis of measurement, namely a positive direction, and the other is along the reverse direction of the gradient coil axis of measurement, namely a negative direction. The first direction is one of two directions along an axis to be measured of the gradient coil. Specifically, the gradient coil includes X, Y, Z three axes (see details below), the axis to be measured of the gradient coil is, for example, the X axis, as shown in fig. 2, fig. 2 only shows five radio frequency coil units coil1 to coil5 in one radio frequency coil (which may be, for example, a head coil), the radio frequency coil units coil1 to coil5 are spatially arranged in a ring shape, and the imaging object is located between the rings formed by the radio frequency coil units coil1 to coil 5. The radio frequency coil unit is preferably arranged in a radio frequency coil, and can be a coil which can wrap the imaging object like a head coil, so that the polarity measurement of three gradient coil axes can be carried out by using one radio frequency coil. As can be seen from fig. 2, of the rf coil units coil1 to coil5, the rf coil unit coil1 and the rf coil unit coil5 may be regarded as two coil units distributed along the X axis of the gradient coil, and may acquire an rf signal of one of the rf coil unit coil1 and the rf coil unit coil5 during detection. If the radio frequency signal of the radio frequency coil unit coil1 is obtained during detection, the radio frequency coil unit coil1 is located in the negative direction along the X axis of the gradient coil relative to the imaging object, namely the first direction is the negative direction along the axis to be detected of the gradient coil; if a radio frequency signal of the radio frequency coil unit coil5 is acquired during the detection, the radio frequency coil unit coil5 is located in a positive direction along the X-axis of the gradient coil with respect to the imaging subject, i.e. the first direction is the positive direction along the axis of interest of the gradient coil.
Step S5: and calculating the signal intensity distribution of the radio-frequency coil unit along the axis to be measured after signal reconstruction based on the radio-frequency signal of the radio-frequency coil unit, and determining a second direction of the radio-frequency coil unit along the axis to be measured relative to the imaging object according to the signal intensity distribution. Wherein the second direction is one of two directions along the axis to be measured of the gradient coil. The specific content of this step is to firstly reconstruct (for example, perform fourier transform) the radio frequency signal of the radio frequency coil unit obtained in step S4, convert the radio frequency signal from a time domain signal to a signal of a frequency domain (spatial domain), determine the second direction as a negative direction along the axis to be measured of the gradient coil if the signal intensity distribution of the transformed radio frequency signal is gradually decreased along the direction of the axis to be measured in the space, and determine the second direction as a positive direction along the axis to be measured of the gradient coil if the signal intensity distribution is gradually increased along the direction of the axis to be measured.
step S6: and determining whether the polarity of the axis to be measured of the gradient coil is reversed or not according to the first direction and the second direction. The specific content of the step is that if the first direction is the same as the second direction, the polarity of the axis to be measured of the gradient coil is determined not to be reversed, and if the first direction is opposite to the second direction, the polarity of the axis to be measured of the gradient coil is determined to be reversed.
The above method of the present invention will be described with reference to the specific drawings, and in this embodiment, the axis to be measured is taken as the X axis as an example, and the radio frequency signal of the radio frequency coil unit coil1 is selected to be acquired, where the radio frequency coil unit coil1 is located in the negative direction along the X axis of the gradient coil with respect to the imaging object, that is, the first direction is the negative direction along the X axis. Specifically, as shown in fig. 3 and 4, the signal intensity distribution of the radio frequency signal along the axis to be measured after calculation and reconstruction can be displayed in the form of one-dimensional projection of the image of the imaging object after fourier transform. Fig. 3 and 4 show two-dimensional images of the imaging object along the X-axis under the two situations of non-reversed polarity and reversed polarity of the X-axis of the gradient coil, wherein the brightness of the two-dimensional image in fig. 3 gradually decreases along the positive direction of the X-axis, and the brightness of the two-dimensional image in fig. 4 gradually increases along the negative direction of the X-axis, it should be noted that the rf signal fed back by the imaging object is stronger at the point where the imaging object is closer to the rf coil unit coil1, so that the rf coil unit coil1 can be determined from fig. 3 to be located in the negative direction along the X-axis of the gradient coil relative to the imaging object, that is, the second direction is the negative direction, and can be determined from fig. 4 to be located in the positive direction along the X-axis of the gradient coil relative to the imaging object, that is, the second direction. Under the condition of acquiring the radio frequency signal of the radio frequency coil unit coil1, that is, the first direction is a negative direction along the X axis, if the two-dimensional image of the imaging object along the X axis is as shown in fig. 3, the second direction is determined to be a negative direction along the X axis, and if the first direction is further determined to be the same as the second direction, the polarity of the X axis of the gradient coil is not inverted; if the one-dimensional projection of the image of the imaging subject along the X-axis is as shown in fig. 4, it is determined that the polarity of the X-axis of the gradient coil is reversed. Of course, the principle of detecting by acquiring the rf signal of the rf coil unit coil5 is the same as that described above, and will not be described herein again.
In other embodiments, a simpler one-dimensional spin echo sequence, in which the one-dimensional spin echo sequence and the feedback pulses of the imaging subject are specifically shown in fig. 6, can be used to test the one-dimensional projections of the water phantom along the X, Y, and Z axes to detect whether the polarities of the X, Y, and Z axes of the gradient coils are reversed. In this embodiment, the waveform is used to display the signal intensity distribution of the radio frequency signal along the axis to be measured (specifically, the X axis) after calculation and reconstruction, as shown in fig. 5. Fig. 5 shows one-dimensional projections of a waveform of an imaging subject along the X-axis in both the case where the polarity of the X-axis of the gradient coil is not reversed and the case where the polarity of the X-axis is reversed, wherein the intensity of the one-dimensional projections of the waveform shown by the solid line in fig. 5 is gradually decreased along the positive direction of the X-axis and the intensity of the one-dimensional projections of the waveform shown by the dotted line is gradually increased along the negative direction of the X-axis. The principle of judging whether the polarity of the X axis of the gradient coil is reversed according to the one-dimensional projection of the waveform is the same as the principle of the two-dimensional image, and is not repeated herein, but the difference between the two principles is that the one-dimensional projection of the waveform only needs to input the radio frequency signal into the spectrometer after the radio frequency signal is calculated and re-input, and the one-dimensional projection of the image needs to display the radio frequency signal on the display through fourier transform.
it should be noted that, when displaying through one-dimensional projection of waveforms, the radio frequency coil unit can acquire a feedback radio frequency signal in the vicinity of the radio frequency coil unit as long as there are hydrogen atoms, so that the one-dimensional projections of the two waveforms in fig. 5 are both in the shape of parabolas, each parabola is formed by two curves that change smoothly and change violently, because the number of hydrogen atoms in the imaging object is huge, and the number of hydrogen atoms in the non-imaging object region around the radio frequency coil unit is much smaller than the number of hydrogen atoms in the imaging object, therefore, the one-dimensional projection of the waveform of the imaging object changes slowly, that is, the curve that changes smoothly in fig. 5 is the one-dimensional projection of the waveform of the imaging object, and the curve that changes violently is the one-dimensional projection of the waveform of the hydrogen atoms in the non-imaging object region around the radio frequency coil unit. The method and principle for detecting whether the polarities of the Y axis and the Z axis of the gradient coil are reversed are the same as those of the method and principle for detecting whether the polarities of the X axis of the gradient coil are reversed, and are not repeated herein.
In the embodiment, the imaging object is a water model sphere, so that the cost can be obviously reduced and the use is convenient.
Referring to fig. 7 and fig. 8, an embodiment of the invention further provides a magnetic resonance scanning system 100, which includes a magnetic resonance scanning apparatus 10 and a computer 12 connected to the magnetic resonance scanning apparatus 10, wherein the computer 12 stores a computer program that can be executed, and the computer program can execute the above-mentioned gradient coil polarity detection method when being executed. In an embodiment, the gradient coil polarity detection method of the present invention includes that the rf coil includes at least three coil units, and respectively obtains rf signals of the three coil units in a first direction (for example, an X direction), a third direction (for example, a Y direction), and a fifth direction (for example, a Z direction) along a to-be-measured axis (an X axis, a Y axis, and a Z axis) of the gradient coil with respect to the imaging object, respectively, and based on the rf signals of the three coil units, respectively calculates signal intensity distributions of the rf signals of the three coil units along the to-be-measured axis (the X axis, the Y axis, and the Z axis) after signal reconstruction, and determines second, fourth, and sixth directions of the three rf coil units along the to-be-measured axis with respect to the imaging object according to the signal intensity distributions of the three coil units;
and determining whether the polarity of the axis to be measured (X axis, Y axis and Z axis) is reversed or not according to the first direction, the second direction, the third direction, the fourth direction, the fifth direction and the sixth direction.
Wherein determining whether the polarity of the axis to be measured is reversed according to at least one of the direction combinations of the first direction and the second direction, the third direction and the fourth direction, and the fifth direction and the sixth direction comprises: if the two directions in the direction combination are the same, determining that the polarities of the axes to be measured of the corresponding gradient coils are not reversed; and
And if the two directions in the direction combination are opposite, determining that the polarity of the axis to be measured of the corresponding gradient coil is opposite.
In particular, in this embodiment, the magnetic resonance scanning device 10 includes a magnetic resonance housing having a main magnet 101 therein, the main magnet 101 may be formed of superconducting coils for generating a main magnetic field, and in some cases, a permanent magnet may be used. The main magnet 101 may be used to generate a main magnetic field strength of 0.2 tesla, 0.5 tesla, 1.0 tesla, 1.5 tesla, 3.0 tesla, or higher. In magnetic resonance imaging, an imaging subject 150, such as a patient, is carried by a patient couch 106, which moves the imaging subject 150 into a region 105 of relatively uniform main magnetic field distribution as the couch plate moves. Generally, for a magnetic resonance scanning apparatus, as shown in fig. 8, the z direction of the spatial coordinate system (i.e. the coordinate system of the apparatus) is set to be the same as the axial direction of the gantry of the magnetic resonance system, the length direction of the patient is generally kept consistent with the z direction for imaging, the horizontal plane of the magnetic resonance system is set to be an xz plane, the x direction is perpendicular to the z direction, and the y direction is perpendicular to both the x and z directions.
the magnetic resonance scanning device 10 further comprises a radio frequency coil, a gradient coil 102, a pulse control unit 111, a gradient signal generation unit 112, a radio frequency pulse generation unit 116, a switch control unit 117, a radio frequency reception unit 118 and an image reconstruction unit 121.
In magnetic resonance imaging, the pulse control unit 111 controls the radio frequency pulse generating unit 116 to generate a radio frequency pulse, which is amplified by the amplifier, passes through the switch control unit 117, and is finally emitted by a radio frequency coil (not labeled) to perform radio frequency excitation on the imaging object 150. The radio frequency coil includes a body coil 103 and a local coil 104, and the radio frequency coil emits a radio frequency pulse typically through the body coil 103 or the local coil 104. The imaging subject 150 generates corresponding radio frequency signals from resonance upon radio frequency excitation. When receiving the radio frequency signals generated by the imaging subject 150 according to the excitation, the radio frequency signals may be received by the body coil 103 or the local coil 104, there may be a plurality of radio frequency receiving links, and after the radio frequency signals are sent to the radio frequency receiving unit 118, the radio frequency signals are further sent to the image reconstruction unit 121 for image reconstruction, so as to form a magnetic resonance image.
The gradient coils 102 may be used to spatially encode radio frequency signals in magnetic resonance imaging. The pulse control unit 111 controls the gradient signal generating unit 112 to generate gradient signals, which are generally divided into three mutually orthogonal directions: gradient signals in the x, y and z directions, which are different from each other, are amplified by gradient amplifiers (113, 114, 115) and emitted from the gradient coil 102, thereby generating a gradient magnetic field in the region 105.
The computer 12 also includes a processor 122, a display unit 123, an input/output device 124, a storage medium 125, and a communication port 126. The pulse control unit 111, the image reconstruction unit 121, the processor 122, the display unit 123, the input/output device 124, the storage medium 125 and the communication port 126 may perform data transmission via the communication bus 127, so as to control the magnetic resonance imaging process. The processor 122 may be composed of one or more processors. The display unit 123 may be a display provided to a user for displaying an image. The input/output device 124 may be a keyboard, mouse, control box, spectrometer, or other related device that supports input/output of the corresponding data stream. Storage medium 125 may be read-only memory (ROM), random-access memory (RAM), a hard disk, etc., and storage medium 125 may be used to store various data files that may be needed for processing and/or communication use, as well as possible program instructions for execution by processor 122. The communication port 105 may be implemented with other components such as: and the external equipment, the image acquisition equipment, the database, the external storage, the image processing workstation and the like are in data communication. Note that a computer program is stored in the storage medium 125, and the program stored in the storage medium 125 can be executed by the processor 122.
When the magnetic resonance scanning system of the present invention is run to execute the gradient coil polarity detection method of the present invention, a water model sphere is usually placed in the local coil 104, and the imaging medium (water) is usually uniformly distributed in the water model sphere. The water film may also in some cases be not spherical but other shapes, such as a cube, a cylinder, etc. The local coil 104 is typically designed in an omni-directional coverage such that the radio frequency coil units can be selected along the direction of the axis under test on either side of the axis under test.
the invention has the beneficial effects that:
(1) the detection data is calculated and evaluated mainly in a magnetic resonance signal one-dimensional projection mode without imaging, so that the detection speed is higher;
(2) The imaging object does not need to be moved in the detection process, so that the detection operation is more convenient;
(3) The imaging object is a common spherical water model, the use is more convenient, and the manufacturing cost is lower.
the above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A method for detecting polarity of a gradient coil, comprising the steps of:
receiving radio frequency signals of an imaging subject by a radio frequency coil, the radio frequency coil comprising at least one radio frequency coil unit;
Acquiring a radio frequency signal of a radio frequency coil unit, the radio frequency coil unit being located in a first direction along an axis to be measured of the gradient coil with respect to the imaging subject;
Calculating the signal intensity distribution of the radio-frequency signals along the axis to be measured after signal reconstruction based on the obtained radio-frequency signals of the radio-frequency coil unit, and determining a second direction of the radio-frequency coil unit along the axis to be measured relative to the imaging object according to the signal intensity distribution; and
And determining whether the polarity of the axis to be measured is reversed or not according to the first direction and the second direction.
2. the method of claim 1, wherein determining whether the polarity of the axis under test is reversed based on the first direction and the second direction comprises:
If the first direction is the same as the second direction, determining that the polarity of the axis to be measured of the gradient coil is not reversed; and
and if the first direction is opposite to the second direction, determining that the polarity of the axis to be measured of the gradient coil is reversed.
3. The method for detecting the polarity of a gradient coil according to claim 1, further comprising, before the receiving the radio frequency signal of the imaging object by the radio frequency coil:
And emitting radio frequency pulses through a radio frequency coil to carry out radio frequency excitation on the imaging object, and exciting the imaging object to emit radio frequency signals.
4. The method for detecting the polarity of a gradient coil according to claim 3, wherein before the radio frequency coil emits the radio frequency pulse to perform the radio frequency excitation on the imaging object, the method further comprises:
an imaging subject is placed within the radio frequency coil.
5. the method for detecting the polarity of a gradient coil according to any one of claims 1 to 4, wherein the imaging object is a spherical water phantom.
6. the method for detecting polarity of gradient coil according to any of claims 1-4, wherein the signal intensity distribution is displayed in the form of one-dimensional projection waveform along the gradient coil axis of interest.
7. the method for detecting polarity of a gradient coil according to any one of claims 1 to 4, wherein the signal intensity distribution is displayed in the form of a two-dimensional image along the axis to be measured of the gradient coil.
8. A magnetic resonance scanning system comprising a magnetic resonance scanning apparatus and a computer, wherein the computer comprises a processor, a storage medium and a computer program stored on the storage medium and executable on the processor, wherein the computer program when executed by the processor is operable to perform a method of detecting polarity of a gradient coil, the method comprising:
Receiving radio frequency signals of an imaging subject by a radio frequency coil, the radio frequency coil comprising a plurality of radio frequency coil units;
acquiring a plurality of radio frequency signals of a plurality of radio frequency coil units, the plurality of radio frequency coil units being located in a corresponding first direction, third direction and/or fifth direction along the axis of interest of the gradient coil relative to the imaging subject;
On the basis of the radio-frequency signals, calculating signal intensity distribution of the radio-frequency signals along the axis to be measured after signal reconstruction, and determining a second direction, a fourth direction and/or a sixth direction of the radio-frequency coil units relative to the imaging object along the axis to be measured according to the signal intensity distribution; and
And determining whether the polarity of the axis to be measured is reversed or not according to at least one group of direction combinations formed by the first direction, the second direction, the third direction, the fourth direction, the fifth direction and the sixth direction.
9. The magnetic resonance scanning system of claim 8, wherein determining whether the polarity of the axis-of-interest is reversed based on at least one of the combination of directions consisting of the first and second directions, the third and fourth directions, and the fifth and sixth directions comprises:
If the two directions in any group of direction combinations are the same, determining that the polarities of the axes to be measured of the corresponding gradient coils are not reversed; and
And if the two directions in any one group of direction combinations are opposite, determining that the polarity of the axis to be measured of the corresponding gradient coil is reversed.
10. A storage medium having a computer program stored thereon, the computer program, when being executed by a processor, performing the steps of the method as set forth in any one of the claims 1 to 7.
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